It has been generally established that magnesium (hereinafter abridged as Mg) is an element which can markedly improve mechanical properties of aluminum-base alloys (hereinafter called Al-base alloys), and normally 0.5 to 5.5% by weight Mg is contained in Al-base alloys. It has been also well known that Mg-Al alloys just as Fe-Si-Mg, Ni-Mg, Cu-Mg and Ca-Si-Mg alloys are widely used as a purifying additive such as for deoxidation, desulfurization and dephosphorization of steel or non-ferrous alloys, and also used as a graphite spheroidizing agent for cast iron.
Also magnesium alloys for casting, die casting and extrusion contain Al, Zn, Mn and Si.
For production of Mg-containing alloys and Al-based or Mg-based alloys which are used as a metallurgical alloying additive, Al-Mg alloy, Al-Mn-Mg alloy, Al-Zn-Mg alloy or Al-Si-Mg alloy is used for addition of elements other than Al or Mg, and these intermediate alloys are used for the purpose of improving the reaction rate of Mg or dissolution yield of Mg. The use of these intermediate alloys provide technical advantages such that the chemical property of Mg, namely the explosive vapourization of Mg can be effectively prevented, that the melting point of Mg can be favourably lowered so that the dissolution rate of Mg in the molten metal can be increased, and that the yield of alloying elements can be increased. Further, Mg in the form of alloys with other element or elements has advantages that not only the deterioration of Mg quality during transportation and storage can be effectively prevented, but also safety can be assured.
The most common conventional art for production of magnesium alloys as mentioned above comprises maintaining elements other than Mg at a temperature high enough to melt the alloys to be obtained (about 700.degree. C. for Al-Mg alloy, and about 1400.degree. C. for Fe-Si-Mg alloy) quickly immersing a predetermined amount of Mg in the lump form in the molten heat with consideration taken to the possible loss of Mg by oxidation or vapourization by means of a plunge to fully dissolve Mg therein, pouring the heat into a mold, cooling and solidifying the heat, and if necessary, crushing the solidified alloy into lumps or granules.
The above conventional art not only has economical disadvantages that the loss of Mg during melting and crushing is considerable, but also is dangerous, and undesirable from the aspect of hygiene, and also troublesome.